JT-60U MONTHLY SUMMARY

March 1997

OPERATION AND CONFINEMENT PHYSICS

The main objectives of operation / confinement physics in 1997 is to
contribute to (1) Sustainment of high integrated performance ( high H-factor,
high-beta-N, high-bootstrap-fraction ) with QDT=0.3-0.5 under full non-inductive
current drive at Ip~2MA by using high triangularity shape and NNB-CD, (2)
Sustainment of high performance reversed shear enhanced mode with QDT=0.3-0.5
and (3) Sustainment of ELMy H-mode with H-factor~2 at a high density sufficient
for remote radiative cooling. Other key subjects are as follows: (4) Analyses
of H-mode characteristics (in particular at a high density) under the new
divertor condition. (5) Development and demonstration of feedback controls
for density, neutron production rate and radiation. Time response of profiles
to the externally applied heating power , momentum, current and particles
will be systematically analyzed not only for physics understandings but
also for design study of new advanced feedback control systems. (6) Systematic
study related to major disruption and halo current. (7) Detailed analyses
of profile effects on confinement and stability. Formation of both internal
and edge transport barriers will be studied by changing current and rotation
profiles. Concerning the beta-limit, we will focus on the limit in steady-state.
For sustainment of high performance reversed shear discharges, current /
pressure driven ideal / resistive instabilities will be studied in detail.

CURRENT DRIVE AND HIGH ENERGY PARTICLE PHYSICS

Experiment plan in 1997 was discussed. Main experimental subjects in
the field of current drive and high energy particle are the current drive
and sustainment of high performance plasmas with NNB and TAE modes with
NNB and/or ICRF.

Recent results from current drive with NNB, confinement of ICRF-driven
protons, fast ion behavior in sawtooth crash and ICRF-driven TAE modes were
presented in the Meeting of the Japan Society of Plasma Science and Nuclear
Fusion Research and the Meeting of Physical Society of Japan.

DIVERTOR AND BOUNDARY PHYSICS

The main issues for divertor study in 1997 are 1) simultaneous realization
of radiative divertor and good confinement of core plasmas, 2) understanding
of fundamental divertor functions in the new W-shaped divertor such as heat
flux reduction, deuterium and helium pumping, reduction in back flow of
neutrals and impurities etc. and 3) geometrical effect of the W-shaped divertor.
High density H-mode plasmas will be main targets for these studies. Reverse
shear plasmas will be also studied as targets, which leads to an advanced
fusion plasma concept. High triangularity configuration will be used in
these experiments.

The construction of the W-shaped divertor for JT-60U is now under way.
New divertor diagnostics are under installation; Ionization gauges, bolometers,
reciprocating divertor Langmuir probe, horizontal Langmuir probe, divertor
interferometer. The operating test of fast shutter valves for controlling
divertor pumping was done. The shutter speed was about 1.3 sec for opening
full aperture and 0.4 sec for 1/4 aperture. They are being installed to
the divertor pumping ports.